It is known in the art relating to engine intake manifolds to provide a manifold assembly including a manifold having a plurality of air intake passages connected with a plenum and having injector pockets connecting with the air passages. Top feed fuel injectors secured in assembly with a separate fuel rail are received in the injector pockets for selectively delivering fuel to the air intake passages to create a combustible air fuel mixture for delivery to the cylinders of an associated engine. Side mounted electrical connectors provide for connection of the injectors to an actuating electric power source.
An alternative manifold assembly provides an internal common fuel passage that acts as a fuel rail connecting with a plurality of injector pockets. Bottom feed fuel injectors are secured in the injector pockets and receive fuel from the common fuel passage through bottom feed openings. The fuel enters the bottom feed injectors between injection valve seats at the nozzle end of the injectors and an actuating coil and armature which actuate the injection valve through an axially extending rod or needle valve.
The top feed fuel injection system has provided better performance than the bottom feed system which has led to wide usage of the top feed system in spite of the additional costs associated with the separate fuel rail and additional subassembly operations involved in its manufacture.